Wyle operates three screen rooms and one FCC Approved Contractor Open Area Test site and performs EMC testing (emissions and immunity) to a variety of standards including:
- MIL-STD 461/462
- FCC Part 2, 15 and 18 Electromagnetic Tests and Certification using our ANSI C63.4 compliant site
- EMC Directive for Europe (includes EN61000 series and EN550XX series of tests)
- NASA Specification MSFC Spec. 521
- EPRI TR-102323
- SAE J1211 and individual automaker requirements
- SAE J551/J1113
- Magnetic Field Interactions to MIL-E-16400
- VCCI JapanBellcore GR-1089-Core (NEBS)
- FCC Part 68 (Analog systems)
- TIA 631
- US Nuclear Regulatory Commission Guide 1.180
EMC Lab Tips
The formidable task of meeting product compliance requirements can become very difficult if the wrong test laboratory is selected or if there is insufficient preparation for certification testing. This can be particularly true in the case of electromagnetic compatibility (EMC) testing.
For instance, some firms spend needless time and money on redundant testing using 
multiple labs to complete their testing, rather than taking advantage of "one-stop shopping" at a full-service lab using "harmonized" procedures. Others use labs that are unable to provide design and debugging support, thus forcing products that fail out of the lab and then back to the start of the queue when they are ready for retesting. Even though a product has been "designed for EMC," there are other important items to take into account to make the testing process as economical and expeditious as possible. Here are some suggestions to help simplify the certification effort.
Choice of Test Facilities
It is important to choose a lab that is capable of performing all test protocols required. The lab must also be accredited by the proper authorities in accordance with industry and agency requirements, including any necessary foreign accreditations or recognitions. For instance, FCC Part 15 testing performed at labs accredited by A2LA or NVLAP can be used as a basis for Declarations of Conformity (DOCs) and this will eliminate approval time at the FCC. All approvals required, both domestic and foreign, must be determined and coordinated with the test lab.
If many similar tests are necessary, the lab should be capable of working to a "harmonized" worst-case test plan, thus eliminating redundant and unnecessary testing. The lab chosen should be capable of discriminating which tests must be performed and those that need not be. Since some EMC test standards provide for selection of applicable test methods, considerable cost savings can be had by testing to the specific methods necessary.
The lab should be willing to perform "quick-look" or "pre-scan" testing at an economical fixed rate. This can be used to cost-effectively identify EMC problems early in the product development cycle. The lab should also have the capability of troubleshooting the design if compliance problems are encountered during testing. Its engineers should be able to support "debugging" and assist with shielding, filtering, bonding and grounding techniques, and associated materials, if their assistance is required.
A visit to the lab can be an important discriminator as it allows further familiarization with the lab's capabilities, facilities, equipment and personnel. It is also important to note the lab's convenience relative to lodging and transportation so that any future trips to the lab will be as efficient as possible.
Preparation for Testing
Once a test laboratory is selected, there are several important preparation activities that should be taken into account. If a new design will be tested, it's important to have the cognizant design engineer at the test site or on-call. Not only will this ensure that the test article will be operated properly, but unexpected issues can be addressed much faster and easier with a decision-maker on-site. It would be even better to have an EMC design engineer made available, by either the manufacturer or the test laboratory.
Be sure that all documentation required by the lab is made available beforehand. This package should include:
- Product Description with dimensions and application information
- Schematics
- Assembly Drawings
- Technical Manuals
- Unit Label
- Brand/Model Name Information (for multiple listings)
If there are regulatory agency documentation requirements and/or fees, be sure that they are accounted for in terms of scheduling and budgeting. Also, determine who will be responsible for any agency submittals. Preparation for immunity testing can be particularly important. Ideally, the test program should be designed to stop and flag error conditions and stress levels.
Prepare to have two test specimens available to expedite the process and also as back-up in case of functional failures. A complete set of test support equipment must also be available, including software. It must be capable of fully exercising the specimen in "typical" use mode or to generate agency specified operating conditions, such as, the ANSI/FCC "H" pattern used for exercising video display units.
Be sure that sufficient cable lengths are provided to connect support equipment to the test specimen in the lab. Some labs require cable runs of 50-100 feet for the distance between their open area sites and the areas that must house test article support equipment.
Don't forget to take special care in packaging the test article for shipment and mark it specifically to the attention of the cognizant lab person. On-time delivery is typically very important because independent labs have specific timeframes set aside for each test job and missing a window can impact the schedule significantly.
During Testing
While at the laboratory, there are several items to keep in mind over the course of the test program. One of the most important is to work closely with the laboratory personnel to familiarize them with the operation and other aspects of the test article. Flexibility and patience may be required as schedules may have to be altered to accommodate unforeseen test failures. If so, it's possible that various test programs will interfere with one another, so each program has to allow for some "give and take." It's a good idea to allow a little extra time as a contingency for these events.
The on-site representative should also be prepared for possible periods of inactivity while tests are in process. This is a good opportunity to work on other projects, so be sure the lab provides customer offices and related support.
EMC Lab Testing Checklist
- Choose a lab with all of the necessary capabilities and credentials.
- Use a lab capable of EMC design and debugging support.
- Test as soon as possible for pre-compliance.
- Have the cognizant person on-site.
- Prepare a thorough documentation package.
- Try to have at least two test specimens available.
- Ensure sufficient cable lengths for support equipment.
- Take extra care in packaging test specimens for shipment.
- Allow extra time to cover the unexpected.